Display omitted •Surface defects were reduced via positive duct bias on a 1 µm thick ta-C coating.•Surface defect reduction increased the sp3 fraction.•Carbon transfer layer was formed as spikes/droplet made the surface of Si3N4 ball rough.•Pore defects increased wear debris size and, thus, the friction coefficient. Surface defects of tetrahedral amorphous carbon coatings are typically defined as spikes, droplets, and pores. In this study, a hybrid filtering method using a fixed physical and electrical filter (duct bias voltage) in a filtered cathodic vacuum arc system was used to control the surface defects. The introduction of the duct bias can control to trap the negatively charged macro-particles which is transported to the base material due to a floating potential and duct wall sheath that depend on the positive voltage. The applied positive duct bias voltage was 10, 15, 20, and 30 V. The results of this experiment revealed that as the duct bias voltage increased up to 30 V, the spikes and droplets were almost completely removed on the tetrahedral amorphous carbon surface and only the pores remained. The pores could not create a rough surface for the relative motion between interfaces due to which the friction coefficient increased as the duct bias voltage increased up to 30 V. It was concluded that the spike and droplet defects were positive elements and were required to introduce a carbon-based transfer interface and maintain a stable coefficient of friction.